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Background: Predicting long-term survival after admission to hospital is helpful for clin i cal, administrative and research purposes. The Hospital-patient One-year Mortality Risk (HOMR) model was derived and internally validated to predict the risk of death within 1 year after admission. We conducted an external validation of the model in a large multicentre study. Methods: We used administrative data for all nonpsychiatric admissions of adult patients to hospitals in the provinces of Ontario (20032010) and Alberta (2011-2012), and to the Brigham and Women's Hospital in Boston (2010-2012) to calculate each patient's HOMR score at admission. The HOMR score is based on a set of parameters that captures patient demographics, health burden and severity of acute illness. We determined patient status (alive or dead) 1 year after admission using population-based registries. Results: The 3 validation cohorts (n = 2 862 996 in Ontario, 210 595 in Alberta and 66 683 in Boston) were distinct from each other and from the derivation cohort. The overall risk of death within 1 year after admission was 8.7% (95% confidence interval [CI] 8.7% to 8.8%). The HOMR score was strongly and significantly associated with risk of death in all populations and was highly discriminative, with a C statistic ranging from 0.89 (95% CI 0.87 to 0.91) to 0.92 (95% CI 0.91 to 0.92). Observed and expected outcome risks were similar (median absolute difference in percent dying in 1 yr 0.3%, interquartile range 0.05%-2.5%). Interpretation: The HOMR score, calculated using routinely collected administrative data, accurately predicted the risk of death among adult patients within 1 year after admission to hospital for nonpsychiatric indications. Similar performance was seen when the score was used in geographically and temporally diverse populations. The HOMR model can be used for risk adjustment in analyses of health administrative data to predict long-term survival among hospital patients., The life expectancy of individual patients can be important for both medical decision-making and research. Patients with a short life expectancy may choose to defer preventive treatments, screening interventions or [...]

ABSTRACTSeasonal vaccination remains one of the best interventions to prevent morbidity and mortality from influenza in children. Understanding the characteristics of parents who vaccinate their children can inform communication strategies to encourage immunization. Using a cross-sectional study, we described parental characteristics of people who reported vaccinating their children against influenza during 2018/2019 in a cohort of Canadian digital immunization record users. Data was collected from a free, Pan-Canadian digital vaccination tool, CANImmunize. Eligible accounts contained at least one parental and one “child/dependent” record. Each parental characteristic (gender, age, family size, etc) was tested for association with pediatric influenza vaccination, and a multivariate logistic regression model was fit. A total of 6,801 CANImmunize accounts met inclusion criteria. After collapsing the dataset, the final sample contained 11,381 unique dyads. Influenza vaccination was reported for 32.3% of the children and 42.0% of the parents. In the multivariate logistic regression analysis, parents receiving the seasonal influenza vaccine were most strongly associated with reporting pediatric influenza vaccination (OR 17.05, 95% CI 15.08, 19.28). Having a larger family size and fewer transactions during the study period was associated with not reporting pediatric influenza vaccination. While there are several limitations to this large-scale study, these results can help inform future research in the area. Digital technologies may provide a unique and valuable source of vaccine coverage data and to explore associations between individual characteristics and immunization behavior. Policy makers considering digital messaging may want to tailor their efforts based on parental characteristics to further improve pediatric seasonal influenza vaccine uptake.

Introduction: Since the beginning of the pandemic, numerous public health measures such as COVID-19 vaccines, vaccine mandates and vaccination certificates have been introduced to mitigate the spread of COVID-19. Public opinion and attitudes towards these measures have fluctuated in response to the dynamic political, social, and cultural landscape of the pandemic. Methods: We conducted a time-series study consisting of national cross-sectional surveys between November 2021 to March 2022 to evaluate the Canadian public’s attitudes towards COVID-19 vaccine mandates and vaccine certificates. Results: When examining public sentiment towards COVID-19 vaccine certificates and proof of vaccination measures, there was a shift in responses over time. The proportion of participants “strongly supporting” these measures decreased from 66.0 to 43.1% between W25(Capacity Limits), −W32 (Mask Mandate Removed), whereas “strongly oppose” was the second most common response and rose from 15.9 to 20.6% during this same time period. Concurrently, when examining participants views surrounding mandates, many participants believed that their province was reopening at “about the right pace”, which remained relatively stable over time (33.0–35.4%) between W28 (Emergency Act)–W32 (Mask Mandate Removed). Conclusion: Our study’s findings on the public’s attitudes towards COVID-19 vaccine mandates and vaccine certificates in Canada may aid to guide and streamline the implementation of future similar public health interventions. Future research should include extended follow-up and a more comprehensive examination of trust in government institutions and polarized perspectives on vaccine mandates.

Optimal performance is desired for decision-making in any field with binary classifiers and diagnostic tests, however common performance measures lack depth in information. The area under the receiver operating characteristic curve (AUC) and the area under the precision recall curve are too general because they evaluate all decision thresholds including unrealistic ones. Conversely, accuracy, sensitivity, specificity, positive predictive value and the F1 score are too specific—they are measured at a single threshold that is optimal for some instances, but not others, which is not equitable. In between both approaches, we propose deep ROC analysis to measure performance in multiple groups of predicted risk (like calibration), or groups of true positive rate or false positive rate. In each group, we measure the group AUC (properly), normalized group AUC, and averages of: sensitivity, specificity, positive and negative predictive value, and likelihood ratio positive and negative. The measurements can be compared between groups, to whole measures, to point measures and between models. We also provide a new interpretation of AUC in whole or part, as balanced average accuracy, relevant to individuals instead of pairs. We evaluate models in three case studies using our method and Python toolkit and confirm its utility.

Several reports have described glomerular disease relapse after coronavirus disease 2019 (COVID-19) vaccination, but without proper controls, determining whether this association is real or due to chance is not possible. In this population-level cohort of 1105 adult patients with stable glomerular disease, a first dose of a COVID-19 vaccine was not associated with relapse risk; however, receiving a subsequent vaccine dose was associated with a two-fold higher risk of relapse. The increase in absolute risk associated with vaccination was low (1%–5%), and the majority of affected patients did not require a change in immunosuppression or biopsy. These results represent the first accurate assessment of the relative and absolute risks of glomerular disease flare associated with COVID-19 vaccination and underscore the favorable risk-benefit profile of vaccination in patients with glomerular disease.

Background: Hospital readmissions are important patient outcomes that can be accurately captured with routinely collected administrative data. Hospital-specific readmission rates have been reported as a quality-of-care indicator. However, the extent to which these measures vary with different calculation methods is uncertain. Methods: We identified all discharges from Ontario hospitals from 2005 to 2010 and determined whether patients died or were urgently readmitted within 30 days. For each hospital, we calculated 4 distinct observed-to-expected ratios, estimating the expected number of events using different adjustments for confounders (age and sex v. complete) and different units of analysis (all admissions v. single admission per patient). Results: We included 3 148 648 admissions to hospital for 1 802 704 patients in 162 hospitals. Ratios adjusted for age and sex alone had the greatest variation. Within hospitals, ranges of the 4 ratios averaged 31% of the overall estimate. Readmission ratios adjusted for age and sex showed the lowest correlation (Spearman correlation coefficient 0.48-0.68). Hospital rankings based on the different measures had an average range of 47.4 (standard deviation 32.2) out of 162. Interpretation: We found notable variation in rates of death or urgent readmission within 30 days based on the extent of adjustment for confounders and the unit of analysis. Slight changes in the methods used to calculate hospital-specific readmission rates influence their values and the consequent rankings of hospitals. Our results highlight the caution required when comparing hospital performance using rates of death or urgent readmission within 30 days., Readmission rates are used to gauge and compare hospital performance and have been reported around the world. (1-4) These rates create great public interest and concern regarding the local quality [...]

Cannabis use in pregnancy has increased1,2, and many women continue to use it throughout pregnancy3. With the legalization of recreational cannabis in many jurisdictions, there is concern about potentially adverse childhood outcomes related to prenatal exposure4. Using the provincial birth registry containing information on cannabis use during pregnancy, we perform a retrospective analysis of all live births in Ontario, Canada, between 1 April 2007 and 31 March 2012. We link pregnancy and birth data to provincial health administrative databases to ascertain child neurodevelopmental outcomes. We use matching techniques to control for confounding and Cox proportional hazards regression models to examine associations between prenatal cannabis use and child neurodevelopment. We find an association between maternal cannabis use in pregnancy and the incidence of autism spectrum disorder in the offspring. The incidence of autism spectrum disorder diagnosis was 4.00 per 1,000 person-years among children with exposure compared to 2.42 among unexposed children, and the fully adjusted hazard ratio was 1.51 (95% confidence interval: 1.17–1.96) in the matched cohort. The incidence of intellectual disability and learning disorders was higher among offspring of mothers who use cannabis in pregnancy, although less statistically robust. We emphasize a cautious interpretation of these findings given the likelihood of residual confounding.

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ABSTRACTPrevious studies from low-resource countries have highlighted concerns surrounding non-specific effects of whole-cell pertussis vaccination, particularly in females. We sought to examine the effects of sex and birth weight on health services utilization following first exposure to whole-cell pertussis vaccine. Using a self-controlled case series design and by calculating relative incidence ratios (RIRs), we compared the relative incidence of emergency department visits and/or hospital admissions between sexes and between birth weight quintiles. Females had a higher relative incidence of events following vaccination compared to males (RIR = 1.13, 95% CI: 0.99, 1.30), which persisted after adjustment for birth weight (RIR = 1.12, 95% CI: 0.97, 1.28). We also observed a trend of increasing relative incidence of events over decreasing quintiles of birth weight; infants in the lowest quintile had a 26% higher relative event rate compared to the highest quintile, which was robust to adjustment for sex (Unadjusted RIR = 1.26, 95% CI: 1.01, 1.56; Adjusted RIR = 1.23, 95% CI: 0.99, 1.53). The risk of all-cause health services utilization immediately following vaccination, was elevated in female infants and infants having lower birth weight. Further study is warranted to determine if vaccine dosing should take infant weight into account.

Preterm birth (PTB) is the leading cause of morbidity and mortality in children globally, yet its prevalence has been difficult to accurately estimate due to unreliable methods of gestational age dating, heterogeneity in counting, and insufficient data. The estimated global PTB rate in 2020 was 9.9% (95% confidence interval: 9.1, 11.2), which reflects no significant change from 2010, and 81% of prematurity-related deaths occurred in Africa and Asia. PTB prevalence in the United States in 2021 was 10.5%, yet with concerning racial disparities. Few effective solutions for prematurity prevention have been identified, highlighting the importance of further research.

The transformative power of artificial intelligence (AI) is reshaping diverse domains of medicine. Recent progress, catalyzed by computing advancements, has seen commensurate adoption of AI technologies within obstetrics and gynaecology. We explore the use and potential of AI in three focus areas: predictive modelling for pregnancy complications, Deep learning-based image interpretation for precise diagnoses, and large language models enabling intelligent health care assistants. We also provide recommendations for the ethical implementation, governance of AI, and promote research into AI explainability, which are crucial for responsible AI integration and deployment. AI promises a revolutionary era of personalized health care in obstetrics and gynaecology.

Preterm birth (PTB) is a leading cause of morbidity and mortality in children under 5 globally, especially in low-resource settings. It remains a challenge in many low- and middle-income countries to accurately measure the true burden of PTB due to limited availability of accurate measures of gestational age (GA), 1sttrimester ultrasound dating being the gold standard. Early prediction of pregnancies at high risk of PTB remains an even broader challenge globally. Metabolomics biomarkers are a promising area of research that could provide tools for both early identification of high-risk pregnancies, and for estimation of GA and preterm status of newborns postnatally. Several recent studies have investigated the utility of metabolomics markers from prenatal maternal biofluids (blood, urine, or cervicovaginal or amniotic fluids) to predict risk of PTB, and postnatal neonatal and umbilical cord blood for estimation of GA and preterm status of the newborn. We review the state of evidence, with an emphasis on postnatal GA estimation with applications to low-resource settings.

Patients with cancer have an increased risk of venous thromboembolism (VTE). Currently, several VTE risk prediction tools have been developed to identify candidates for primary VTE thromboprophylaxis. However, the availability of reliable and highly discriminatory prediction models for VTE risk assessment in cancer patients is limited, warranting further improvement of VTE risk stratification strategies. The implementation of biomarkers in risk assessment models might lead to refined VTE risk prediction, but it remains to be more comprehensively investigated. In this systematic review and meta-analysis, we aimed to evaluate and summarize all candidate biomarkers and their association with cancer-associated VTE.

Inherited thrombophilia and cancer are both recognized risk factors for venous thromboembolism (VTE). In the general population, the risk of thrombosis is increased in patients with inherited thrombophilia, but the role of inherited thrombophilia on the risk of cancer-associated VTE remains controversial. The objective of this study was to summarize and determine whether cancer patients with inherited thrombophilia gene mutations have an increased risk of developing VTE.

ABSTRACTT-cell receptor excision circle levels are a surrogate marker of T-cell production and immune system function. We sought to determine whether non-pathological levels of infant T-cell receptor excision circles were associated with adverse events following immunization. A self-controlled case series design was applied on a sample of 231,693 children who completed newborn screening for severe combined immunodeficiency in Ontario, Canada between August 2013 and December 2015. Exposures included routinely administered pediatric vaccines up to 15 months of age. Main outcomes were combined health services utilization for recognized adverse events following immunization. 1,406,981 vaccination events were included in the final dataset. 103,007 children received the Pneu-C-13 or Men-C-C vaccine and 97,998 received the MMR vaccine at 12 months of age. 67,725 children received the varicella immunization at 15 months. Our analysis identified no association between newborn T-cell receptor excision circle levels and subsequent health services utilization events following DTa-IPV-Hib, Pneu-C-13, and Men-C-C vaccinations at 2-month (RI 0.94[95%CI 0.87-1.02]), 4-month (RI 0.82[95%CI 0.75-0.9]), 6-month (RI 0.63[95%CI 0.57-0.7]) and 12-month (RI 0.49[95%CI 0.44-0.55]). We also found no trends in health services utilization following MMR (RI 1.43[95%1.34-1.52]) or varicella (RI 1.14[95%CI 1.05-1.23]) vaccination. Our findings provide further support for the safety of pediatric vaccinations.

ABSTRACTVaccine certificates have been implemented worldwide, aiming to promote vaccination rates and to reduce the spread of COVID-19. However, their use during the COVID-19 pandemic was controversial and has been criticized for infringing upon medical autonomy and individual rights. We administered a national online survey exploring social and demographic factors predicting the degree of public approval of vaccine certificates in Canada. We conducted a multivariate linear regression which revealed which factors were predictive of vaccine certificate acceptance in Canada. Self-reported minority status (p < .001), rurality (p < .001), political ideology (p < .001), age (p < .001), having children under 18 in the household (p < .001), education (p = .014), and income status (p = .034) were significant predictors of attitudes toward COVID-19 vaccine certificates. We observed the lowest vaccine-certificate approval among participants who: self-identify as a visible minority; live in rural areas; are politically conservative; are 18–34 years of age; have children under age 18 living in the household; have completed an apprenticeship or trades education; and those with an annual income between $100,000–$159,999. The present findings are valuable for their ability to inform the implementation of vaccine certificates during future pandemic scenarios which may require targeted communication between public health agencies and under-vaccinated populations.

ABSTRACTBackground:Intussusception has been identified as a rare adverse event following rotavirus immunization. We sought to determine the incidence of intussusception among infants in Canada both before and after introduction of rotavirus immunization programs. Methods:We used Canadian Institute for Health Information (CIHI) Discharge Abstract Database (DAD) to identify infants under 1 y of age who were admitted to a Canadian hospital, which the exception of Quebec, which does not submit data to CIHI, with a diagnosis of intussusception (ICD-10 code K56.1, and ICD-9 code 560) between January 1st, 2003 and December 31, 2013. We compared rates of intussusception hospitalization before and after rotavirus vaccine program introduction. Rates were adjusted for calendar year, age (in months), sex and region using Poisson regression models. Denominator data for infants under 1 year, stratified by age in months, were obtained from Statistics Canada.Results:Annual intussusception hospitalization rates ranged from 20-30 per 100,000 infants over the study period, with no evidence of a trend over time. Intussusception hospitalization rates were highest in infants 4 to <8 months and lowest in those under 2 months or between 10 and <12 months. Males had higher rates than females both overall and within each age group. The rate of intussusception hospitalization after rotavirus vaccine program introduction was 22.4 (95% CI: 18.3, 27.4) compared to 23.4 (95% CI: 21.5, 25.4) per 100,000 before program introduction. Conclusions:We have described baseline intussusception hospitalization rates for infants in Canada and have found no evidence of a change in rate after implementation of routine rotavirus immunization programs.

BackgroundTobacco-related illnesses are leading causes of death and healthcare use. Our objective was to determine whether implementation of a hospital-initiated smoking cessation intervention would reduce mortality and downstream healthcare usage.MethodsA 2-group effectiveness study was completed comparing patients who received the ‘Ottawa Model’ for Smoking Cessation intervention (n=726) to usual care controls (n=641). Participants were current smokers, >17 years old, and recruited during admission to 1 of 14 participating hospitals in Ontario, Canada. Baseline data were linked to healthcare administrative data. Competing-risks regression analysis was used to compare outcomes between groups.ResultsThe intervention group experienced significantly lower rates of all-cause readmissions, smoking-related readmissions, and all-cause emergency department (ED) visits at all time points. The largest absolute risk reductions (ARR) were observed for all-cause readmissions at 30 days (13.3% vs 7.1%; ARR, 6.1% (2.9% to 9.3%); p<0.001), 1 year (38.4% vs 26.7%; ARR, 11.7% (6.7% to 16.6%); p<0.001), and 2 years (45.2% vs 33.6%; ARR, 11.6% (6.5% to 16.8%); p<0.001). The greatest reduction in risk of all-cause ED visits was at 30 days (20.9% vs 16.4%; ARR, 4.5% (0.4% to 8.7%); p=0.03). Reduction in mortality was not evident at 30 days, but significant reductions were observed by year 1 (11.4% vs 5.4%; ARR 6.0% (3.1% to 9.0%); p<0.001) and year 2 (15.1% vs 7.9%; ARR, 7.3% (3.9% to 10.7%); p<0.001).ConclusionsConsidering the relatively low cost, greater adoption of hospital-initiated tobacco cessation interventions should be considered to improve patient outcomes and decrease subsequent healthcare usage.

ABSTRACTMobile applications have the potential to influence vaccination behavior, including on-time vaccination. We sought to determine whether the use of a mobile immunization app was associated with the likelihood of reporting on-time vaccination in a cohort of 50 childbearing women. In this pilot study, we describe participant reported app use, knowledge, attitudes or beliefs regarding pediatric vaccination and technology readiness index (TRI) scores.To explore if app use is associated with change in attitudes, beliefs or behavior, participants were instructed complete a baseline survey at recruitment then download the app. A follow up survey followed 6-months later, reexamining concepts from the first survey as well as collecting participant TRI scores. Changes in Likert scores between pre and post survey questions were compared and multivariate logistic regression was used to assess the relationship between TRI score and select survey responses. Thirty-two percent of participants perceived that the app made them more likely to vaccinate on time. We found some individuals' attitudes toward vaccines improved, some became less supportive and in others there was no change. The mean participant TRI score was 3.25(IQR 0.78) out of a maximum score of 5, indicating a moderate level of technological adoption among the study cohort population. While the app was well received, these preliminary results showed participant attitudes toward vaccination moved dichotomously. Barriers to adoption remain in both usability and accessibility of mobile solutions, which are in part dependent on the user's innate characteristics such as technology readiness.

Inherited thrombophilia and cancer both independently increase the risk of venous thromboembolism (VTE). However, whether the increased VTE risk associated with inherited thrombophilia exists in cancer patients is less clear.

ABSTRACTRoutine childhood vaccination improves health and prevents morbidity and mortality from vaccine-preventable diseases. There are indications that the COVID-19 pandemic has negatively impacted immunization rates globally, but systematic studies on this are still lacking in Canada. This study aims to add knowledge on the pandemic’s effect on children’s immunization rates with pneumococcal vaccine using self-reported immunization data from CANImmunize. An interrupted time series analysis was conducted on aggregated monthly enrollment of children on the platform (2016–2021) and their pneumococcal immunization series completion rates (2016–2020). Predicted trends before and after the onset of the COVID19-related restriction (March 1, 2020) were compared by means of an Autoregressive Integrated Moving Average (ARIMA). The highest monthly enrollment was 3,474 new infant records observed in January 2020, and the lowest was 100 records in December 2021. The highest Self-reported pneumococcal immunization series completion rate was 78.89%, observed in February 2017, and the lowest was 6.94% in December 2021. Enrollment decreased by 1177.52 records (95% CI: −1865.47, −489.57), with a continued decrease of 80.84 records each month. Completion rates had an immediate increase of 14.57% (95% CI 4.64, 24.51), followed by a decrease of 3.54% each month. The onset of the COVID-19 related restrictions impacted the enrollment of children in the CANImmunize digital immunization platform and an overall decrease in self-reported pneumococcal immunization series completion rates. Our findings support efforts to increase catch-up immunization campaigns so that children who could not get scheduled immunization during the pandemic are not missed.

Background:Prematurity may influence the levels of amino acids, enzymes, and endocrine markers obtained through newborn screening. Identifying which analytes are the most affected by degree of prematurity could provide insight into how prematurity impacts metabolism.Methods:Analytes from blood spots assayed by Newborn Screening Ontario between March 2006 and April 2009 were used in this analysis. We examined the associations between the degree of prematurity and the levels of amino acids, enzymes, and endocrine markers in all newborns with and without adjustment for birth weight, feeding status, sample timing, transfusion, and sex.Results:Our analysis included the following cohorts: 373,819 children born at term (>36?wk gestation), 26,483 near-term children (33–36?wk gestation), 4,354 very premature children (28–32?wk gestation), and 1,146 extremely premature children (<28?wk gestation). Of the amino acids showing consistent trends across categories of prematurity, the levels of three amino acids (arginine, leucine, and valine) were at least 50% different between the cohorts of extremely premature and term children. The levels of 17-hydroxyprogesterone increased with increasing prematurity, while thyrotropin-stimulating hormone values consistently decreased with increasing prematurity. None of the three enzyme markers we examined showed a trend in levels across categories of prematurity.Conclusion:This study demonstrates that children at different stages of prematurity are metabolically distinct. Future research should focus on the mechanism by which specific analytes are influenced by prematurity.

Numerous clinical trials have demonstrated early reductions in cardiovascular events occurring independently of the lipid-lowering effects of statins. These pleiotropic effects have been attributed to antiinflammatory properties, to atherosclerotic plaque stabilization, and more recently to mobilization of endothelial progenitor cells (EPCs). Our aim was to evaluate the evidence supporting statin-induced EPC mobilization in humans. We, therefore, performed a computerized literature search and systematic review of randomized trials to determine the effect of statin therapy and statin dosing on circulating EPC numbers. Our literature search identified 10 studies including 479 patients which met inclusion criteria with publication dates ranging from 2005 to 2011. Seven studies compared statin to nonstatin regimens whereas 3 studied low versus high-dose statin therapy. Reported increases in EPC number ranged from 25.8 to 223.5 with a median reported increase of 70.2 when compared to nonstatin regimens with 7 of 10 studies reporting significant increases. Considerable heterogeneity exists in regard to patient population, statin regimens, and the definition of an EPC within the identified studies. In conclusion, randomized studies in humans suggest that statin therapy mobilizes EPCs into the circulation. Larger randomized studies using uniform definitions are needed to definitively establish this effect.

Using a population-based self-controlled case series design, we examined data on children born between the years 2002 and 2009 in the province of Ontario, Canada. We specifically examined how socioeconomic status (SES) influences rates of adverse events following immunization (AEFI), defined as emergency room visits and / or hospital admissions. For vaccination at 2, 4 and 6 mo combined, the relative incidence of AEFI (95% CI) in the first 72 h after vaccination was 0.69 (0.67 to 0.71). For all three vaccinations combined, we observed no relationship between the relative incidence of an event and quintile of socioeconomic status (p = 0.1433). For the 12-mo vaccination alone, the relative incidence of events (95% CI) on days 4 to 12 following immunization was 1.35 (1.31 to 1.38). We observed a significant relationship between socioeconomic status and vaccination at 12 mo, with lower SES being associated with a higher relative incidence of events (p = 0.0075). When the lowest 2 quintiles of income combined were compared with the highest 3 quintiles, the relative incidence ratio (95% CI) was 0.94 (0.89 to 0.99, p = 0.02). These results translate to 150 additional adverse events in the lower SES quintiles as compared with the higher SES quintiles for every 100,000 children vaccinated, or 1 additional event for every 666 individuals vaccinated. Future studies should explore potential explanations for this observation.

Premature children are at increased risk of complications from vaccine-preventable diseases and should be vaccinated with the routinely recommended childhood vaccines at the same chronological age as full-term infants with the exception of the hepatitis B vaccine for infants of HBsAg-positive mothers. We sought to compare on-time vaccination levels in premature children for recommended vaccinations to levels in children born at term. Using linked health administrative databases, we compared the proportion of term (37+ wks), near term (33-36 wks), very premature (28–32 wks) and extremely premature (≤27 wks) children who received at least one vaccination during the 2-, 4- and 6-month vaccination visits within the recommended time period in the province of Ontario. When we excluded children who were hospitalized at any time during the vaccination window, we identified that vaccination rates were within 3% of each other in the 4 categories examined. However, when we included infants who may have been hospitalized at any point during the on-time window, we observed substantially lower rates in the extremely premature children at 2 and 4 months and in the very premature children at 2 months. Our study identifies the need to confirm whether vaccinations are given while premature children are in hospital during the time of their scheduled vaccinations. Les enfants prématurés courent un risque accru de complications des maladies évitables par la vaccination; ils devraient donc recevoir les vaccins infantiles systématiquement recommandés au même âge chronologique que les nourrissons nés à terme, à l’exception du vaccin contre l’hépatite B pour les nourrissons de mères séropositives pour l’AgHBs. Nous avons voulu comparer, pour les vaccins recommandés, les niveaux de vaccination à temps des enfants prématurés à ceux des enfants nés à terme. À l’aide de bases de données sanitaires administratives liées, nous avons comparé la proportion d’enfants nés à terme (37+ sem.), légèrement prématurés (33-36 sem.), très prématurés (28-32 sem.) et extrêmement prématurés (≤27 sem.) ayant reçu au moins un vaccin durant leurs visites de vaccination à 2, 4 et 6 mois dans les délais recommandés dans la province de l’Ontario. En excluant les enfants hospitalisés à un moment donné durant la fenêtre de vaccination, nous avons constaté que les taux de vaccination se situaient dans une proportion de 3 % les uns des autres dans les quatre catégories examinées. Cependant, en incluant les nourrissons ayant pu être hospitalisés à un moment donné durant la fenêtre de vaccination, nous avons obtenu des taux considérablement plus faibles dans la catégorie des enfants extrêmement prématurés à 2 et à 4 mois, et dans celle des enfants très prématurés à 2 mois. Notre étude souligne le besoin de confirmer si les vaccins sont administrés aux enfants prématurés lorsqu’ils sont hospitalisés au moment de recevoir les vaccins prévus.

Using a population based self-controlled case series study design we examined data on 834 740 children in the province of Ontario, Canada. We observed that when comparing to SGA10 term children (term children born in the lowest 10th percentile of weight for a given gestational age), relative incidence of emergency room visits and admission in the 3 d post 2 mo vaccination progressively decreased in near term [relative incidence ratio 0.89 (95% CI 0.74–1.07)] and very premature children [0.67(0.49–0.93)]. When compared with all term children this decrease in risk is not statistically significant. We speculate that the immune response is reduced in premature children resulting in reduced adverse events. This is masked when comparing to all term children because the reduced birth weight of premature children results in a comparatively increased dose of vaccine. This in turn results in an increased immune response and risk of immediate adverse reactions. Future studies of immune response in premature children should examine the impact of weight at the time of immunization.

Maternal weight during pregnancy impacts the health of both mother and baby. This project investigated associations between maternal pre-pregnancy body mass index (BMI) and the child's future health service utilization.

ObjectiveTo determine whether any association exists between exposure to 2009 pandemic H1N1 (pH1N1) influenza vaccination during pregnancy and negative health outcomes in early childhood.DesignRetrospective cohort study.SettingPopulation based birth registry linked with health administrative databases in the province of Ontario, Canada.ParticipantsAll live births from November 2009 through October 2010 (n=104 249) were included, and children were followed until 5 years of age to ascertain study outcomes.Main outcome measuresRates of immune related (infectious diseases, asthma), non-immune related (neoplasms, sensory disorders), and non-specific morbidity outcomes (urgent or inpatient health services use, pediatric complex chronic conditions) were evaluated from birth to 5 years of age; under-5 childhood mortality was also assessed. Propensity score weighting was used to adjust hazard ratios, incidence rate ratios, and risk ratios for potential confounding.ResultsOf 104 249 live births, 31 295 (30%) were exposed to pH1N1 influenza vaccination in utero. No significant associations were found with upper or lower respiratory infections, otitis media, any infectious diseases, neoplasms, sensory disorders, urgent and inpatient health services use, pediatric complex chronic conditions, or mortality. A weak association was observed between prenatal pH1N1 vaccination and increased risk of asthma (adjusted hazard ratio 1.05, 95% confidence interval 1.02 to 1.09) and decreased rates of gastrointestinal infections (adjusted incidence rate ratio 0.94, 0.91 to 0.98). These results were unchanged in sensitivity analyses accounting for any potential differential healthcare seeking behavior or access between exposure groups.ConclusionsNo associations were observed between exposure to pH1N1 influenza vaccine during pregnancy and most five year pediatric health outcomes. Residual confounding may explain the small associations observed with increased asthma and reduced gastrointestinal infections. These outcomes should be assessed in future studies.